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MG MGB Technical - My starter relay??? photo

In an on going effort to resolve my starting issues I have started to take a deeper look into the wiring and I think that may be the root of some of my starting issues.

I have attached a link to a photo which is my starter relay (well at least I think it is!). I have taken a look at Moss's relay and others, but I do not recognise mine. I would appreciate if you can take a look at the photo and let me know what you think. Its the one next to coil. I have also taken the cover off the fuse box as well. The wiring to the relay does not appear to be "standard"?


GG Ginty

No thats not the correct one,if yours is before 68 it should have the one with the starter button on the end of it.

Ste Brown

Yours looks post 68. If so, should be Lucas (LR6 i think) relay but any 4 pin relay will do. I buy bosch ones because a couple extra bucks buys me a brand name and comfort. Yours looks post 68 and the wiring doesnt look that non standard. My 77 came the same way with a big GM style relay and a GM alt. I undpicked all the "improvements" and put in back to stock with all new bosch relays and Limey relay kit for the lights and fans.

A J Ogilvie

Some clever soul wired in an old Ford starter solenoid in place of where the original relay should be. Some re-wiring is in order. RAY
rjm RAY


Ray is right, it is a Ford starter relay.
Cheap, more reliable than original but not ORIGINAL.


Jean G.
Jean Guy Catford

Thanks for your observations
GG Ginty

Remote starter *solenoids* may have had a button on them, relays never did. What starting problems are you having? There is non-standard wiring there so the 'relay' itself may be the least of your problems.
PaulH Solihull


Thanks... my issues is starting. Now I am wondering if I am opening a can of worms. replaced three starters last year. No I wondering if I have one or two good starters lying around

My B is a Oct 73 manufacture date. Had problen with the alternator not putting out. The battery sounded very weak even though it was "fully" charged. Car hard to start, eventually would only jump start so I replaced the alternator and battery. Car started fine, left it for a day or so and when I went to start all I got was the ignition light and a the loud clonk coming from the solenoid. Left for a few days, still only a clonk. Fiddled around for a while when it would crank over, but the sound of the starter turning over was weak. Battery read 12.7V.

What non-standard wiring are you refering to?. Whats with this starter solenoid when I have one on my starter? Where is the starter relay then! I thought one was needed?
GG Ginty

Much of the wiring, esp the starter related part, is not standard, patched, replaced, and with crappy connectors. Given what we see, there are likely a bunch more similar things elsewhere. The solenoid/relay is not standard, it is being used as a replacement for the real one which is normally just at the top right out-of-sight part of the picture, on the inner fender side panel, behind the fusebox.

You have been fooling with this thing long enough, time to go back to basics and sort it correctly. Several common points for this failure are bad battery cables/connections, bad main feeds off the actual on-starter solenoid, and wiring related to the solenoid/relay/start circuit. The fact that somebody did this indicates that there was a problem, possibly involving burnt wires, and the guy didn't know or didn't care how to fix it correctly.

If you are willing to get a wiring diagram, a voltmeter and pay attention, email me and ask for Electrobabble - we'll make an auto electrickian out of you yet!

FR Millmore

Much as Fletcher says regarding wiring and connections. Slow cranking and clonks can be bad battery (weak could be caused by an iffy alternator) or bad connections. You need to use a voltmeter while cranking. If you see 10v or better on the battery *posts* (not the clamps) then the battery itself is fine, and if it is more than 10v then the implication is there are bad connections towards the starter. If you get the almost the same voltage on the battery cable stud of the starter solenoid then the cable and connections look OK so it could be the solenoid contacts, or possibly the motor itself. Some motors have a link between the solenoid and the motor so putting the meter on here can show which. If you get significantly lower voltage on the battery cable stud of the solenoid than on the battery posts that points to cables and connections. It should be possible to get only a few tenths of a volt dropped between battery and starter, but I have seen as much as 3v lost. Anything approaching a volt difference is worth investigating. If you have twin 6v batteries than you need to do voltage tests on the link cable and connections as well as the main 12v and earth cables and connections. Bad connections between your 'relay' and the starter solenoid can cause that to chatter or clonk so you also need to check the voltage on the starter solenoid spade terminal and compare that with the battery cable stud. These should be the same, a difference indicates bad connections. Likewise a bad connection between ignition switch and your 'relay' could have similar effects, if you can determine which wire operates your relay measure here as well, and that should also be the same voltage as the battery cable stud on the starter solenoid.
PaulH Solihull


Thanks.. I am ruling out the alternator, as it's new of a few weeks ago, same as the battery. I would like to rule out the starter itself, as that was new and the third on in a short period of time AND it developed the clonking soon after install, only to disappear after a few months in the garage over winter. Now it has reappeared again along with slow cranking and no start. I am leaning towards wires somewhere but it does not help me when wiring diagrams don't match up with what I have and the "non-standard" equipment.

GG Ginty

You can't rule out anything based on it's newness unfortunately, only by testing it i.e. in the case of the alternator by measuring voltages under normal working conditions. Three starters would tend to rule out the starter itself, unless they have all been obtained from the same place over a short period of time i.e. a batch problem. Again measuring the voltage when cranking at the starter terminals is the way to go to prove the problem to the cables and connections feeding it or not.
PaulH Solihull

This thread was discussed between 15/12/2010 and 18/12/2010

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